The new generation of short period, high lift cams have been developed to give the best results in large bore engines when used in conjunction with 1.5 ratio, hi-lift rockers. For the small bore range, the stock 1.3 ratio is optimum. In certain instances ratios of 1.7 to 1 are of benefit - but is really only applicable to fully developed race engines.
1.3-1 ratio "Cast" rocker. Reproduced using the very latest casting methods employing a special aircraft release EN8 steel. The valve pad is hardened to 54-56 roc. Correctly profiled pad reduces side loading on valves to a minimum. Particularly effective on small bore engines. Use recommended valve clearances.
1.5-1 ratio hi-lift rocker set. Produced in the same way and material spec as the ‘Cast’ rocker, but to cad-cam developed dimensions. This reduces the weight (15% lighter than stock rocker), whilst ensuring optimum strength. This reduction in weight allows lighter valve springs to be used, and extends rpm potential of the fitted spring by some 5%. Valve clearances should be opened up by 3 thou over recommended settings, although up to 5 thou can prove beneficial with certain combinations. Using the 1.5 ratio not only increases maximum lift, but also means that the valve is open approximately 20% more at any given point - although opening and closing periods remain the same. This vastly improves volumetric efficiency and therefore power output. Fitment of this set to a standard 1275cc engine is similar to fitting a ‘mild’ cam shaft.
1.3-1 Roller rocker set. The ultimate valve gear, maximum efficiency, absolute minimal valve stem side loading, vastly reduced friction and extra rigidity. They have a hard chrome needle roller tip and dual needle roller bearings on the very thick wall shaft, are manufactured in hard anodized aircraft alloy for maximum strength and lightness. The rollers are offset in the arms to link up with valve stems on large bore heads.
1.5-1 hi-lift roller rockers. Specifications as per above.
1.3-1 and roller rocker set for small bore engines. Roller tips are centered in the arm to line up with valve stems, otherwise all other specifications as per above.
1.5-1 hi-lift roller rocker set for small bore engines. Specifications as per above.
1.7-1 big bore roller rocker set. Specifications as per above.
Adjust screw - roller rockers.
Lock nut for adjuster screw - roller rockers.
Individual roller rocker with adjuster/nut, state exact requirement when ordering.
Individual 1.5 rocker for C-AHT436 set.
To compliment our range of mechanical and full roller rocker sets, we now offer a roller tipped alloy rocker set. They use the same billet alloy arm and hard chrome roller tip as the full roller set up, but do not use the needle rollers on the shaft. This allows a competition thick wall mini shaft to be used. Standard adjuster screws and nuts are also employed. All this culminates in a high quality yet infinitely more economical roller rocker set, as the roller tip is the most important factor to reduce valve and guide wear when using modern performance cams. The set comes with 8 rockers, adjuster screws and nuts, competition thick wall shaft and steel posts. To use on small bore heads it is necessary to rearrange the rockers to line up the tips with valve stems.
Set of 8 extra long adjuster screws.
Adjuster screw - fits 12G1221 & C-AHT436/446
Lock nut for above.
Extra lift of around .030" can be obtained with the bushed rockers by using offset bushes, supplied as a set of 8. If these bushes are used, before and after alignment of the rocker pad to valve and stem must be checked and corrected. Invariably in the 1.3 rockers a special set of steel posts are required. It is possible to fit the bushes to the 1.5 rockers, however other means of realignment must be used if correction is required. The easiest way is to drill out the stud holes in the pillars to the next size (i.e. 11/32 inch and 25/32 inch) and push the pillars backwards prior to tightening head and rocker post nuts. It is, however, not recommended to go more than 2 oversizes. To enhance valve gear rigidity and reliability, especially in high-revving engines, there is a super-thick wall rocker shaft available. Heat treating rocker shafts is now no longer done as it greatly accelerates wear of the rocker bushes. It is cheaper and easier to replace a worn shaft than a set of worn bushes; the bushes require reaming to size once fitted.
Set of 8 offset rocker bushes.
Set of 4 steel posts when using offset bushes in standard ratio rockers.
Super thick wall rocker shaft - bushed rockers only (not roller type).
To help rocker pad to valve stem tip alignment and reduce friction the standard springs can be replaced by spacers and shims. The spacer set is sold as a set of 3, the shims are so individually.
Rocker spacer set.
Although there has been a carbon-fibre push rod available for sometime, it is in 5/16" diameter. This somewhat over-engineered size meant that awkward and time consuming alterations to cylinder block and head had to carried out so that they can be a) fitted, and b) work without breakage caused be rubbing. Basically a good idea, but little consideration to fitment, and seemingly no R & D. The number of inquiries we have about the use and fitment of carbon-fibre push rods has been steadily increasing, however sales were limited because of fitting hassles. This prompted us into looking into just why 5/16" diameter rod was necessary, bearing in mind the standard steel item is only 1/4". Somewhat strange as carbon-fibre is known to be stronger size for size than steel.
To cut a long story short, a special jig was made to assess the strength of the standard and 5/16" carbon-fibre rods. We then made a one off push rod in 1/4" carbon-fibre. This was duly tested to be exactly what we wanted. It was one and a half times as strong and exactly half the weight of the standard item, yet would fit without ANY block or head modifications whatsoever. A far better product than standard, and a more sensibly dimensioned item than those previously available.
Extra benefits of a carbon-fibre push rod aside from its extra strength and super light weight, are its massively reduced expansion when hot AND almost total absence of resonance. The two latter benefits apply acutely to modern emission standards for modified road vehicles. Tighter valve clearances can be maintained to help reduce emissions. Carbon-fibre does not resonate, so valve train noise is reduced. In fact when in conjunction with our bushed, alloy, roller tip rockers and an alloy rocker cover - valve train noise is significantly reduced.
5/16 inch diameter carbon-fibre push rod for small bore engines, set of 8
1/4 inch diameter, carbon-fibre push rod for small bore engines, set of 8.
5/16 inch diameter carbon-fibre push rod for large bore engines, set of 8.
1/4 inch diameter carbon-fibre push rod for large bore engines, set of 8.
1/4 inch diameter carbon-fibre push rod for eight port leaded engines. These are .220" longer than standard and necessary to optimize rocker geometry.
Carbon-fibre rods can also be supplied to customer required lengths.